The imperious Novak Djokovic moved into the Paris Masters semi-finals on Friday, battling back from a set down to beat Marin Cilic.

Djokovic's sensational run of form was slightly disrupted in the last eight as Cilic made him work for a 21st consecutive victory in which his emotions threatened to boil over.

The Wimbledon and US Open champion was reeling after losing the first set and still evidently frustrated for the much of the second, before emerging from a nervy third as the 4-6 6-2 6-3 winner.

A fourth straight title remains on the cards - following on from triumphs at the Cincinnati Masters, Flushing Meadows and the Shanghai Masters - but another tough test lies in wait, with either Roger Federer or Kei Nishikori his opponent in the semi-finals.

An intense opener saw steady holds give way to tightly contested games in which break points came and went with some regularity.

Cilic wastefully sent a forehand wide after gaining the upper hand on Djokovic's serve, before the Serbian similarly squandered a chance and then closed his opponent's next opening.

But the Croatian kept the pressure on and, after a phenomenal passing shot prompted another break opportunity, Djokovic went long and slipped behind.

A hold to love saw Cilic end Djokovic's run of 30 straight sets won, but the response was predictably devastating as the soon-to-be world number one took his seventh break point of the match.

The contest appeared to turn on that moment and Djokovic ended the second with another gain as the ball clipped the net to leave Cilic stranded.

However, Cilic threatened to spring another surprise at the start of the third when he followed up a fine hold with a devastating winner to break. Djokovic smashed his racket in response but swiftly drew level again.

It was then the Serbian's turn for a breathtaking hold as the match clock ticked past two hours and he punished the space left by Cilic in the next game, before taking the opportunity to finally serve out victory.